The invention relates to apparatus for cleaning pipelines, and more particularly to improvements in apparatus for cleaning pipelines of finite length. Still more particularly, the invention relates to improvements in apparatus which can be used to clean pipelines with liquid cleaning agents, especially with liquid cleaning agents which contain discrete cleaning elements in the form of sponges or the like.
Commonly owned U.S. Pat. No. 4,607,410 discloses a cleaning apparatus with a four-way flow reversing valve which can change the direction of flow of a liquid cleaning agent through a pipeline of finite length. For example, the cleaning agent is an alkaline solution, an acid, tap water or a disinfectant. The apparatus employs two cylindrical housings which are connected to two ports of the valve and each of which is connected or connectable to one end of a discrete pipeline. The other ends of the pipelines are directly or indirectly connected to each other in order to establish a path for the flow of cleaning agent from one housing, through the pipelines and into the other housing. The cleaning elements which float in the stream of cleaning fluid effect a movement of the valving element in the four-way valve to a different position when they enter one of the housings, and the flow of cleaning agent is then reversed until the cleaning elements reach the other housing, and so forth. If the cleaning agent is tap water, spent water is simply discharged by way of the outlet of the cleaning apparatus. If the cleaning agent is an alkaline solution, an acid or a disinfectant, it is normally gathered in a vessel, regenerated and reintroduced into the pipeline or pipelines to be cleaned. The valving element of the four-way valve has a first port which receives cleaning agent from a suitable source (such as a water tap or the aforementioned vessel), and a second port which communicates with the outlet in one position of the valving element. When the direction of flow of cleaning agent is reversed, the first port communicates with the outlet and the second port receives fresh cleaning agent.
The patented apparatus operates quite satisfactorily. However, the cost of the four-way valve is high because the body of such valve is a complex structure which cannot be readily mass-produced in a single operation. The body must be assembled of several precision-finished parts which must be sealingly secured to each other in order to prevent uncontrolled leakage of fresh or spent cleaning agent.
German Pat. No. 689,234 to Wagner discloses a cleaning apparatus which is connectable to two ends of a pipeline and to a source of pressurized liquid cleaning agent. The housing or body of the apparatus has a longitudinally extending passage with ends connected to the ends of the pipeline to be cleaned, and six radially extending ports. Pairs of ports are connected to each other by channels. A reciprocable valving element in the passage of the body can establish or interrupt paths for the flow of liquid between selected ports, and its ends carry sieves for cleaning agent. The diameter of each sieve matches the diameter of the passage in the body. When the interstices of one of the sieves are sealed by cleaning elements in the body of liquid agent which fills the pipeline to be cleaned, the pressure of cleaning agent at the respective axial end of the valving element rises and the latter is caused to move axially to a different position to thus establish communication between different sets of ports in the body of the patented apparatus and to thereby reverse the direction of flow of cleaning agent in the pipeline.
Commonly owned German Pat. No. 33 47 003 discloses a method of and an apparatus for manipulating cleaning elements which swim in and with the liquid cleaning agent. When the apparatus is not in use, the cleaning elements are immersed in a body of sterilizing liquid which is admixed to the cleaning agent when the apparatus is put to renewed use. A similar method is disclosed in the aforementioned commonly owned U.S. Pat. No. 4,607,410.
German Auslegeschrift No. 25 48 308 of Cooper discloses a rather complex system of valves which are to be used in a hydrostatic system including a hydraulic pump and a hydraulic motor and serving to drive motor vehicles or to actuate heavy-duty machinery or other types of machines. Cooper employs a system of valves with two coaxial valves each of which has a discrete movable valving element and which are designed to reverse the direction of flow of a hydraulic fluid along its path.
German Offenlegungsschrift No. 2 262 036 of Kurschner discloses a system of valves wherein a reciprocable displacing element can lift one of two spherical valving elements off its seat so as to connect a control line with that one of two conduits wherein the pressure of fluid is higher.
U.S. Pat. No. 3,734,132 to Kuhnelt discloses a shuttle valve which can be used as a pneumatic selector switch to alternately direct incoming impulses from one input to either of two different outputs.
French Pat. No. 973,215 to Fioretti discloses a valve which is to be used in motor vehicles and wherein a solid cylindrical plunger is reciprocable in a valve body between two end positions to establish or interrupt the flow of fluid between selected ports of the body. The purpose of the patented valve is to reduce the likelihood of leakage of fluid and, to this end, the plunger is surrounded by one or more annular seals which are made of leather or another deformable material.